A centrifugal pump device has at least one impeller (16), a circulation connection between a delivery side (22) of the at least one impeller (16) and a suction side (20) of the at least one impeller (16), and a valve arrangement (30, 46) in said circulation connection (44, 54). The valve arrangement (30, 46) has a first valve mode providing a pressure dependent shut-off valve (46) in the circulation connection. The valve arrangement (30, 46) allows a change between the first valve mode and at least one further valve mode. The at least one further valve mode provides at least one fixed closing degree of the circulation connection (44, 54).

Embodiments of the present disclosure provide a method for controlling a fan, a system, and an air conditioner. The method includes: turning off a first bridge arm group in an inverter of the fan; applying a preset driving signal to a second bridge arm group in the inverter; detecting an electrical signal of a stator of the fan after the preset driving signal is applied; determining an initial state of the fan according to the electrical signal of the stator of the fan, wherein the initial state of the fan includes a downwind forward state, a static start state, or an unwind reverse state; and providing the fan with a control signal matching the initial state of the fan according to the initial state of the fan.

Provided are a mask device and a method for controlling the same. The mask device includes a mask body configured to cover a nose and mouth of a user, a first air cleaner connected to one side of the mask body, and a second air cleaner connected to the other side of the mask body. Also, the mask device includes a first suction fan module installed in the first air cleaner, a second suction fan module installed in the second air cleaner, and an exhaust fan module disposed in the mask body.

A fan system includes a motor, a rotatable hub, and a plurality of fan blades. The motor is coupled with the hub by a hollow drive shaft, such that the drive system of the fan system is gearless. The motor is controlled by a PFC-based control module, which is in communication with sensors that are configured to sense parameters associated with operation of the fan system. The control module is configured to react in certain ways to certain conditions detected by the sensors, such that the fan system uses feedback-based control algorithms. A remote control panel is in communication with the control module. The remote control panel is operable to display fault conditions detected by the sensors. Blade retainers prevent fan blades from falling when a fan blade breaks free from the hub. Pins prevent the hub from falling when the hub breaks free from the rotor.

A motor unit comprises a motor controller, a motor, and a Hall sensor, where the motor controller is used for driving the motor. The motor controller comprises a switch circuit, a control unit, a phase signal generating unit, and an operational amplifier. The control unit generates a plurality of control signals to control the switch circuit. The motor comprises a rotor, a silicon steel plate, and a coil. To increase a success rate of starting a forward rotation, the silicon steel plate may have an asymmetrical structure, such that a fan blade is inclined to a forward rotation direction in a still state. When a Hall voltage is zero, the motor controller may start the motor and switch phases.

An embodiment of the present invention provides a control device comprising: an electric detection unit which detects an electric physical quantity relating to a head capacitor provided between a DC power supply and an inverter switching element; and a protection control unit which controls the inverter switching element in accordance with a change in the electric physical quantity so that no electric current flows to the head capacitor.

An air pump with automatic stop of inflation and deflation includes a housing provided with a first air inlet/outlet and a second air inlet/outlet. The inside of the housing is provided with a knob mechanism, an inflation and deflation linkage and an air channel switching mechanism which is connected to the product to be inflated or deflated through the second air inlet/outlet. The inflation and deflation linkage controls the air channel switching mechanism to be operatively connected to the knob mechanism which controls the displacement of the air channel switching mechanism so as to be communicated with the product to achieve inflation or deflation or not to be communicated with the product to achieve automatic stop of inflation or deflation.

A computing device has a fan housing that includes a dual rotor fan with a first rotor and a second rotor. The computing device also includes a controller communicatively coupled to the dual rotor fan. The controller is operable to detect a failure associated with the first rotor. In response to detecting the failure, the controller is operable to drive the second rotor at a higher speed than a fan-speed at which the second rotor was being driven before the failure.

A fan control circuit with temperature compensation includes an on-off unit and a speed adjustment unit. When determining that a loading is greater than or equal to an adjustable start threshold according to a load signal, the on-off unit controls the fan entering a working mode. In the working mode and determining that the loading is less than a speed-adjusting threshold, the on-off unit maintains a speed value of the fan at a first fixed speed. When determining the loading is greater than or equal to the speed-adjusting threshold, the speed adjustment unit adjusts the speed value according to the loading. The speed adjustment unit generates a speed displacement according to a temperature signal to compensate the speed value.

Provided is a protection method for use in fan malfunctions, applicable to an electronic device, and effective in preventing the electronic device from being overheated. The electronic device includes a fan, temperature sensor, and processor. The method includes steps of: limiting the processor's performance, upon determination that not only is the fan's rotation speed greater than or equal to a predetermined upper rotation speed limit, but the electronic device's temperature sensed by the temperature sensor is also greater than or equal to a predetermined upper temperature limit; determining whether the fan's rotation speed is less than or equal to a first restored rotation speed when the fan's rotation speed is determined to be less than the predetermined upper rotation speed limit; and stopping the limiting of the processor's performance when the fan's rotation speed is determined to be less than or equal to the first restored rotation speed.